Attachment plug



Dec. s, 192s.- .1,564,817

R.' B. BENJAMIN E-r AL ATTACHMENT PLUG `mma May 1o. 1920 2 sheets-sim: 1

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A R. B. BENJAMIN ET AL ATTACHMENT PLUG Filed May 10, 1920 2 Sheets-Sheet 2 I El Vento r6:

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Patented Dec. S, 1925.

UNITED.. lSTATES PATENT OFFICE. y

REUBEN BENJAMIN, OF CHICAGO, AND CHESTER E. WARNER, OF BERWYN, ILLINOIS, ASSIG'NORS T O BENJAMIN ELECTRIC MANUFACTURING COMPANY, OF CHICAGO,

ILLINOIS, A CORPORATION ILLINOIS.

ATTACHMENT PLUG'.

To cZZ whom t may concern:

Be it known that we, REUBEN B. BEN- IAMIN, acitizen of the United States, resid- 'ing at Chicago, in the county of Cook and State of Illinois, and CHESTER E. WARNER, a'citizen Aof the United4 States, residing at Berwyn,- inthe countyoi Cook and State of Illinois, have invented certa-in new and 'useful Improvements in Attachment Plugs, OEE which the following is a full, clear, conoise, and exact description, reference being had to the accompanying drawings, forinmg a part of this specification. Our invention relates` to attachment plugs, and'more specifically to attachment plugs Jfor heavy duty, inwhich provision has to be made to prevent injury to the contacts due to the heavy current.

Une of the objects of our invention isto provide an improved plug for heavy duty in which provision is'inade for preventing injury to the contacts in making VVthe connection. We accomplishl this by providing a switch mechanism carried by the plug,

r which switch mechanism is automatically moved to on positionv when the plug is inserted in the receptacle.

Further objects of our invention will appear Yfrom the description to follow and trom the claims.

In the drawings, in which an embodiment ot our invention is shown:

plus; i

Fig. 2"is a top plairview of the'plug shown in Fig..1; Figy is an axial section o'f the plug shown in Fig. 1; Y 1 'K Fig. 4 is an axialv sectioiiof .the plug on the line 4-4 of Fig. 3;

Fig. 5 is a transverse sectional-view on the line 5 5 of Fig. 3;

Fig. 6 is ajtransverse sectional view onl j j n oll the switch. The switch lever'23 is en; ,gaged by and moved by aninsulating button the. line 6-G of Fig. 3; Y

Fig. 7 is a section through the switch mechanism on theline 7--7 of Fig'. 5.

F ig; 8 is a bottoni viewot the 'insulating 'i ,y

' the plug 'is screwed. intotlie socket, the insuvlating button 28 will bear on theswitch lever plug base; j r Fig; S) Vis YVtop view ot an insulating lower base; Y

Fig. 1 is a. side elevation of an attachment Fig. 10 is a bottom view of the lower base; a ,v j y Fig. 11 is a perspective view of the switch lever; and j Fig. 12 is'a detail view of the switch arm.'l In order to give a general ideaof the construction shown, it is here stated, that it comprises a swivel plugior screwing into an Edison socket, the swivel shell contact of ythe plug being provided with a flexible extension handle, the plug itselfcontaining a snap switch mechanism actuated by the center contact of theplug, and being provided with binding terminals for conductors leading from the plug, and with cord-grip means for relieving these binding terminals from strain due toa pull on the conductors.

Referring now vto the construction in detail, the plug shown comprises an insulating base 15, a center contact 16 supported thereby, a swivel shell contact 17 rotatably mounted with respect thereto, aliexible extension handle 18 connected with the swivel shell contact 17, a switch mechanism 19 mounted in the insulating basev 15, binding terminals I20 and 21 forthe conductors lead-- ing from the plug respectively, and an insulating screw cord-grip member 22 for gripping the conductors to relieve the bindf ing terminals 2O and 21 from strain.

Referring particularly now tothe con-k struction of the switch mechanism 19, this is of the snap switch type, sometimes referred to as a toggle switch, and comprisesan oscillatable switch lever 23, an oscillatablev switch arm 24, a link 25 extending between the switch 'lever 23 and the switch arm 24,

a coilfcompre'ssion spring 26 surrounding the link 2 5, and exerting a pressure tend-k ing to force the switch arm 24 away from the switch rlever 23 and acoil-torsion-spring 27 ,l tending to move the4 switchv lever into a positionv corresponding to the oitv position 2S, which inturiiis connected to more with the `center VContact lt ofthe plug so that when 23' .t0 910V@ thaw-ita@ lever??? te a posities '37 of the wiring terminal 21d. This binding and v conductingstrip36 andis threaded'into-.a nut base 39, the

which will cause the switch to snap to the Start the switch arm in motion to the on on position. It will thus be seen that the position. The switch lever 23 may be a U- member 23 is in eiiect a bell-crank member' shaped sheet metal stamping, having a bearv acting between the plunger 23 and the link ing portion 43 for engagement with the fork- 25. ed end of the'link 25, andhaving position- The switch mechanism controls the elecing lugs 44 for holding the Vlinl-r25 against trical connection between the center contact lateral movement. This stamping is also l16 and the binding terminal 21, the other provided with an opening 45 toreceive the binding terminal 20 being always electriend 46 of the coil-torsion spring 27, the-other cally connected with the threaded shell conend of which spring may bear against the tact`17. The control of the circuit from the web portion of the channel-shaped switch center contact 16 to the wiring'terminal 21 frame 40.

is eected by the cooperation of the switch Y The wiring terminal 2O is electrically conarm 24 with two spring contact members 29 nected with the shell contact 17 by means of and respectively, the spring contact 29 the sliding contact sleeve or cap 47, and a being' always electrically connected with the conducting strip 48, leading :from the slidcenter Contact 16, and the spring .Contact 30 ing contact 47 tothe binding screw 49 of the being always electrically connected with the binding .terminal 20. This sliding .contact wiring terminal 21, and the switch arm 24 member 47 .may be a sheet metal stamping, which is o1n conducting material serving to and may, in addition toV serving as acontact, make orl break the connection between'the act also to hold the insulating base 39 in contacts 29 and' 30. The spring contact 29 place with respect to the insulating base 15.

is formed as a partY of an integral sheet It isy provided with an'inwardly-extending metal stamping, this stamping comprising flange portion which `extends underneath in, addition to the UZ-shaped contact portion the flange portion 51 of the insulating base 2,9 a .conducting strip'. portion 31 lying 39, and it has portions in its upper edgedeagainst theside of the recess in which the pressed inwardlyas indicated 5,2 into deswitch meehanism'is located, and a contact pressions or grooves 53 in thesides ofthe Paneel-327 Wlihlhas a .Sliding .Corr-1.0. with insulating base 1.5 .to secure the @schifting e Contact million fiihli colita@ Porti@ lilelilber 471i@ the insulating base. `15,10 1.119.121 33vinfelectrieal connection with the center the two insulating .bases together.

contact 16. To assist in holdingthe contact The conducting member'49 khas a portion 29 in place, the'stamping isprovided with an clamped between lthe flange portion v50 of the lli-shaped extension 34 at its lower end, which contact 47 and the .flange portion 51 rof the lits into a correspondingly shaped recess in insulating base 39. The binding screw 49 the insulating base 1.5, to hold the lower end extends through an opening in .the .member of the stamping against movement. y The 48 .and is threaded into a nut 54 located in center contact 16 is formed as a part of the a recess in the insulating base 39.

integral sheet metal stamping, comprising F or gripping. the conductors .which are a cylindrical portion 35 surrounding the inconnected with the binding terminals 20 and Y sul-ating button 28, in yaddition to the slid- 21, the cord-grip member 22 is internally ing con-tact portion 33. threaded, and is screwed onto the externally The contact portion 30 is formed as a part threaded portion 55 of ythe insulating base of an integral sheet metal stamping, which 39. stamping comprises iny addition to the U- When the cord-grip member 22y is screwed Shaped contact portion 30, a `bent conducting up, it pinches the cord between Vthe annular strip portion 3,6 extending across the recess `shoulder portion 56 -of the cord-grip memin which the switch mechansim is located, and ber and the tapered abutment 57 of the inextending downwardly to the binding screw sulating base 39. Thebinding terminals 2O p 21 are located in recesses or-poekets v58 Screw 37 exteildstrllroush shoreline ill the and 59 in .Opposite Sides. of the insulating threads of the insulating base beine .interrupted at tlieseleeses; f

For positioning the Vinsulating base- 39 y with respect to they insulating base,v 15,7 the The switch arm 24 ,comprises a U-shaped base 15 is provided w-i-tha downwardly exsheet metal stamping,` `which ispivotally, tending lug or boss 60 which engages. in a mounted in a switch frame 40, by means ofa recess 6l in the flange portion-.oftheinsulat- Pvet pin 451,.'l10l1 'nivel' ein also iiivetally ing base .39'-

38, which is seated in a recess in thel insulering base 319, Which- Supports .the binding terminals 20 and 21. f

Supports the SWtCfll later. 23.

The Switch. .frame 40j may .have e lus 42 struck er tlierefrela vlief?ie.neassise1.1i"with? llelnli 2.5., tesi-.Vs aresitv le t0 the' Wits-i. arm. flies/ladine pressure 0f the compression spring 26Y is insi'ithcieiit to The flexible 'har-.ldlc 1.8'se0nr1eeteflt9. the threadeslllell .Contact-17. by meansof. ashet metal cup-shaped stamping 62, the. lower prton 0i Whicliis .Secured 6311s serenita'ble manner, to the iiexible handl,e 1 z8,` an d the upper edge of which is anged over an insulating disc 64, which disc 64 is in turn secured to the threaded shell contact 17. The threaded shell contact is beaded Vover this insulating disc y64 as indicated at'65, the upper portion of this bead serving as a contact portion for engagement with the sliding contact 47. The usual insulating sleeve or collar 66 is provided for insulating the lower portion of the-threaded shell contact 17 when the latter is in engagement with the receptacle contact. The cup-shaped stamping 62 is provided with a pair of openings 67 on opposite sides to afford access to the cord-grip member 22 to` enablel the cord to be gripped after the plug is wired and assembled.

rlhe circuit through the plug has been outlined in connection with the description'oi' the switch mechanism. Assuming that the plug is screwed int-o the socket (and hence that the switch is in on position) the circuit will be from the center Contact 16 through the sleeve portion 35, sliding contact 33, switch contact portion 32, conducting portion 31, contact 29, switch arm 24, contact 30,l conductor 36, to the binding terminal 21, thence through whatever translating device is connected with the plug to the wiring terminal 20, to the Contact member 47 to the threaded shell contact 17.

In wiring the plug, the inner construction including the two insulating bases 15 and 39 and the parts carried thereby are removed from the threaded shell contact 17, the plugV member 22 being screwed off from the inf sulating base 39, to permit this removal, the conductors are led up through the liexible handle 13, and through the cord-grip member 22 and the threaded shell contact 17 and are secured to the wiring terminals 20 and 21, and the interior construction is then slipped back into the shell and the cordgrip member 22 screwed onto the threaded portion of the insulating base 39, to hold the parts together and to grip the cord.

lVhen the plug is to be inserted into the socket, the threaded shell contact 17 is positioned properly with respect to threaded shell of the socket and is screwed into the socket, the flexible handle 18 being u sed if the socket is otherwise difficult of access. As the threaded shell contact is screwed'into the socket, the center contact 16 will come into engagement with the center contact of the socket, and will be moved relatively to the rest of the plug, to cause the push button member 23 to actuate the switch lever 23, to cause the switch to snap vfrom oit to on position to quickly complete the circuit. This quick completion of the circuit prevents burning of the contacts and other undesirable eilects which result when the cir-cuit :is completed slowly and uncertainly as is apt to be the case with the ordinary screw shell plug..

Similarly, when the plug is screwed outV of the socket,the spring 27 will force the insulating button 28, which carries the center contact, outwardly'V with respect to the rest of the plug, and will keep the center contact 16 in engagement 'with thecenter contact of the socket .for a time, 'until the spring 27 has moved the switch leverL 23 to a position which will cause'the switch blade 24 to be moved to ofiq position, thus quickly breaking the circuit at two points and preventing arcing and burning of the contacts. c

This breaking of the circuit at a vpoint other than between the center contacts ofthe plug-in socket` also prevents the danger of arcing from the center contact of the socket to the center contact of plug and thence to the shell contact of the receptacle, which is apt to take place in heavy duty plugs, which have no provision to ipreventthis aref ing.

Having thus described our invention,

what we claim as new and desire to secure by Letters Patent is:

1. An attachment plug comprising a body-portion, a center contact mounted thereon, a shell contact swiveled thereon,

said body-portion being insertable in said shell contact at the entering end thereof, said body-portion having an extension projecting outwardly from said threaded shell contact, and two wiring terminals mounted on said extension, one of said terminals being electrically connected with the center contact, and the other terminal being electrically connected with the threaded shell contact, said extension and wiring terminal being withdrawable with said body portion from the entering end of said shell contact.

2. An attachment plug comprising a twopart insulating base comprising an inner and outer part, a threaded shell contact swiveled about said insulating base, said inner base part beingrecessed and open` at its outer end, a switch mechanism located in said recess and insertable and removable through said open outer end, wiring vterminals mounted on the outer part of said insulating base, a contact mounted on said outer base part, and extending intoy said recess for engagement with said switch mechanism, and another contact mounted on said outer base part extending up and slidably engaging'said swivel shell contact.

3. An attachment plug comprising a twopart insulating` base comprising an inner and outer part, a threaded shell contact swiveled abouty said kinsulating base, Vsaid inner base part being recessed and open at its outer end, a switch mechanism located in said recess and insel-table andremovable through said open outer end, "wiring terminals mounted on the outer vpart ofv said linsulating base, a contact mounted 011 said outer ybase part and extending into said recess 'for engagement with said switch mechanism, and means engaging said outer base part for holding said swivel shell in position. i

t. An" attachment plug comprising a twopart insulating base comprising inner and outer parts, a threaded shell contact swiveled on said insulating base, a recess in said insulating base exposed on separating the parts of the base, switch mechanism in said recess, and means for holding the two parts of the base together comprising a sliding contact member engaging said threaded vshell contact.

5. 'A switch plug comprising an insulating base,-a shell Contact mounted thereon, a center contact member mounted thereon to slide longitudinally thereof, and a switch mechanism for vcontrolling the plug circuit comprising Va 'switch blade locatedv substantially within said shell Contact and oscillatable back and forth, a spring shiitable back and forth pasta dead center to cause quick action of thev switch blade, and a spring shifting member operated by said slidable contact member.

6. A switch plug comprising an insulat-f back and forth past a dead center to cause quick action of the switch blade, and a pivoted spring shifting member operated by said slidable'contact member.

In witness whereof, we have hereunto subscribed our names.

REUR-EN B. BENJAMIN. CHESTER E. WARNER. 

